The planetary gear arrangement of an automatic transmission allows the transmission to reduce or enhance the input speed received from the power source. The planetary gear arrangement's components include a ring gear, planetary carrier with at least one pinion gear, and a sun gear. The gears of the planetary gear arrangement encircle the main shaft of the transmission and through engagement with a series of clutches influence the output speed of the main shaft.
Given their essential functionality, planetary gear arrangements are often analyzed for improvements to their manufacturing processes and overall costs. The sun gear, for example, can be separated from its shaft to simplify the manufacturing process for each respective member. Such an alteration can create new demands on neighboring components within the planetary gear arrangement.
Optimizing the fuel economy and ensuring proper cooling of all the internal components in the hybrid transmission can also be critical. Planetary components can also assist in directing the flow of a lubricant to transmission components thereby reducing fatigue and increasing the transmission's lifecycle.
An electromechanical transmission is described U.S. Provisional Application Ser. No. 60/531,528, entitled “Two-Mode Compound-Split, Hybrid Electro-Mechanical Transmission Having Four Fixed Ratios,” Schmidt et al., filed Dec. 19, 2003, assigned to General Motors Corporation and hereby incorporated by reference in its entirety.